Split charge relay replacement

[NorwayWesty95]

Hi guys,
newly registered lurker here, and of course I need your help...

The problem is that my 1995 California Coach no longer charges the battery from the engine.
I changed to an upgraded battery last year, it holds a charge fine and it charges perfectly from the outside socket.
After doing my research on here I was able to locate the relay below the fridge, and lo and behold it was damaged (somehow one pin has broken off).

The relay I have is a BOSCH 0 332 002 150.​

I've seen some of you guys rocking a ...168 instead of the 150, it's the same but with an additional resistor. ​

I suppose that should work for me as well? Well, unfortunately I managed to order a ..156 model instead, which has a diode instead of the resistor.​

Here's the diagram for it. Does anyone know if this will work?


Any help incredibly appreciated, I don't really know my way around automotive electronics.

 

[ArcticMatt]

Usually the diodes are just to suppress spikes. What’s the voltage specification for that relay? You wouldn’t necessarily have to stick with a Bosch relay. Lots of folk use these relays. I’ve got one in my other van https://webshop.durite.co.uk/WebRes...chnical Information/701-800/0-727-33 spec.pdf


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[NorwayWesty95]

Hey, another Norwegian! Takk for svar

Both the original and my new relay are 12V 75A, that's why I thought it should work.
Thanks for your suggestion about the Durite one, that could certainly be something to try if my new Bosch one doesn't work.

 

[yossarian]

Yeah, those are suppression diodes for the coil. Just make sure 85 is pos and 86 neg.

 

[Steve1]

Yeah, those are suppression diodes for the coil. Just make sure 85 is pos and 86 neg.

Shouldn't it be 86 pos and 85 neg otherwise no current will be able to follow through the diode connected to 85.

 

[yossarian]

Shouldn't it be 86 pos and 85 neg otherwise no current will be able to follow through the diode connected to 85.

Yes! Sorry. . The second diode will prevent operation if incorrectly connected.

 

[ArcticMatt]

Hey, another Norwegian! Takk for svar

Both the original and my new relay are 12V 75A, that's why I thought it should work.
Thanks for your suggestion about the Durite one, that could certainly be something to try if my new Bosch one doesn't work.

Hei Hei. I’m an Englishman living in good old Norway. Still learning the lingo If you are ever near Bodø, keep an eye out for a red high-top


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[NorwayWesty95]

Thanks guys. How do I know which pin is positive though?
Two of the pins are in a plug anyway (85 and 86) so if I don't want to hack the plug I can only switch cables on 87 and 30.

 

[yossarian]

Thanks guys. How do I know which pin is positive though?
Two of the pins are in a plug anyway (85 and 86) so if I don't want to hack the plug I can only switch cables on 87 and 30.

Option a poke a wire into the plug and measure continuity to chassis ground.

Option b hook it up. If it works the polarity is ok. If not the second diode will stop the relay from working but prevent damage.

 

[NorwayWesty95]

Thanks for your suggestions, I tried hooking the ..156 relay up but unfortunately it doesn't work. It seems to do the reverse of what I want, since I can measure the leisure battery's voltage on both sides of the relay with the engine running. With the engine off I've got leisure battery voltage on one pin and car battery voltage on the other. I also tried switching the positions of the 85 and 86 cables, but it didn't seem to change anything.

The good news is that I now know for certain that my original relay is the problem. It has a loose pin, and if I manage to shove that pin far enough into the relay box I get the desired electrical behaviour. I guess this means I could fix everything using gaffa tape, but it doesn't feel completely safe somehow.
I will order a new model ..168 relay, that one has decent availability here (meaning just one more week of the season wasted hopefully). Chances are that will solve my problem.

 

[NorwayWesty95]

Hei Hei. I’m an Englishman living in good old Norway. Still learning the lingo If you are ever near Bodø, keep an eye out for a red high-top


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Not exactly the worst place in the world to go camping That's just a ferry ride away from the Lofoten islands for you non-locals.
I've actually never driven my van that far north, just a regular car. And yeah, red is the way to go, marsala red I think mine is called.

 

[yossarian]

I can measure the leisure battery's voltage on both sides of the relay with the engine running. With the engine off I've got leisure battery voltage on one pin and car battery voltage on the other.

Is this not the desired behaviour? If the voltage is the same the relay is likely closed.

 

[NorwayWesty95]

Is this not the desired behaviour? If the voltage is the same the relay is likely closed.

With the engine off this is desired behaviour yes. With the engine on however I expect the alternator current on both sides of the relay?

Another symptom that something is wrong is the overhead display in the van. My battery indicator doesn't disappear and I don't get 13+ volts with the engine on. Nothing changes in the display when I turn the engine on, it still shows the leisure battery voltage (11.9 volts in this case).

 

[yossarian]

It sounds like your vehicle bus feed may have a high resistance.

You could try run a 12V light bulb from the alternator side of the relay. If no light and voltage drops close to zero this hypothesis is confirmed.

Your meter may be able to read the resistance directly. Try from vehicle battery positive to alternator side of the relay. Try from vehicle battery negative to leisure battery negative. How many ohms in each case?

Buzzing for voltage has complications. A high resistance will give you full voltage if the relay is open. Only under load do you see the effects of resistance.

Attempting to detect DC current with a normal meter will usually result in a meter with a blown fuse. You need a hall effect sensor to do it non intrusively.

 

[sidepod]

Have you checked the DIP switches on the rear of the overhead display?
They’re switched according to battery type and number.

Search on the subject and you’ll find the correct configuration.
It’s been posted here several times.

 

[NorwayWesty95]

Thanks for all your help guys, I simply switched my broken model 150 relay with a new model 168 replacement relay and that did the trick.
Onwards we go